The best way to think about the pandas data structures is as flexible
containers for lower dimensional data. For example, DataFrame is a container
for Series, and Panel is a container for DataFrame objects. We would like to be
able to insert and remove objects from these containers in a dictionary-like
fashion.

Also, we would like sensible default behaviors for the common API functions
which take into account the typical orientation of time series and
cross-sectional data sets. When using ndarrays to store 2- and 3-dimensional
data, a burden is placed on the user to consider the orientation of the data
set when writing functions; axes are considered more or less equivalent (except
when C- or Fortran-contiguousness matters for performance). In pandas, the axes
are intended to lend more semantic meaning to the data; i.e., for a particular
data set there is likely to be a “right” way to orient the data. The goal,
then, is to reduce the amount of mental effort required to code up data
transformations in downstream functions.

For example, with tabular data (DataFrame) it is more semantically helpful to
think of the index (the rows) and the columns rather than axis 0 and
axis 1. And iterating through the columns of the DataFrame thus results in more
readable code:

All pandas data structures are value-mutable (the values they contain can be
altered) but not always size-mutable. The length of a Series cannot be
changed, but, for example, columns can be inserted into a DataFrame. However,
the vast majority of methods produce new objects and leave the input data
untouched. In general, though, we like to favor immutability where
sensible.

pandas development began at AQR Capital Management in
April 2008. It was open-sourced at the end of 2009. AQR continued to provide
resources for development through the end of 2011, and continues to contribute
bug reports today.

Since January 2012, Lambda Foundry, has
been providing development resources, as well as commercial support,
training, and consulting for pandas.

pandas is only made possible by a group of people around the world like you
who have contributed new code, bug reports, fixes, comments and ideas. A
complete list can be found on Github.

pandas is a part of the PyData project. The PyData Development Team is a
collection of developers focused on the improvement of Python’s data
libraries. The core team that coordinates development can be found on Github. If you’re interested in contributing, please
visit the project website.

=======
License
=======
pandas is distributed under a 3-clause ("Simplified" or "New") BSD
license. Parts of NumPy, SciPy, numpydoc, bottleneck, which all have
BSD-compatible licenses, are included. Their licenses follow the pandas
license.
pandas license
==============
Copyright (c) 2011-2012, Lambda Foundry, Inc. and PyData Development Team
All rights reserved.
Copyright (c) 2008-2011 AQR Capital Management, LLC
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials provided
with the distribution.
* Neither the name of the copyright holder nor the names of any
contributors may be used to endorse or promote products derived
from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
About the Copyright Holders
===========================
AQR Capital Management began pandas development in 2008. Development was
led by Wes McKinney. AQR released the source under this license in 2009.
Wes is now an employee of Lambda Foundry, and remains the pandas project
lead.
The PyData Development Team is the collection of developers of the PyData
project. This includes all of the PyData sub-projects, including pandas. The
core team that coordinates development on GitHub can be found here:
http://github.com/pydata.
Full credits for pandas contributors can be found in the documentation.
Our Copyright Policy
====================
PyData uses a shared copyright model. Each contributor maintains copyright
over their contributions to PyData. However, it is important to note that
these contributions are typically only changes to the repositories. Thus,
the PyData source code, in its entirety, is not the copyright of any single
person or institution. Instead, it is the collective copyright of the
entire PyData Development Team. If individual contributors want to maintain
a record of what changes/contributions they have specific copyright on,
they should indicate their copyright in the commit message of the change
when they commit the change to one of the PyData repositories.
With this in mind, the following banner should be used in any source code
file to indicate the copyright and license terms:
#-----------------------------------------------------------------------------
# Copyright (c) 2012, PyData Development Team
# All rights reserved.
#
# Distributed under the terms of the BSD Simplified License.
#
# The full license is in the LICENSE file, distributed with this software.
#-----------------------------------------------------------------------------
Other licenses can be found in the LICENSES directory.